In three collaborating hospitals, the efficacy of cyproheptadine HCL (Periactin) and behavior modification will be evaluated, singly and in combination, in the hospital treatment of anorexia nervosa with respect to restoration of body weight, reduction of behavior typical of anorectics, enhancement of mood, relief of psychic distress, and personality change. Forty female anorectics in each of two other collaborating hospitals and 32 in our hospital will be randomly assigned to one of the four combinations of Periactin vs. placebo, and behavior modification vs. no behavior modification, and will be followed and assessed for 35 days. The treatments will be assessed for additive vs. interactive effects and will be compared for rapidity of action and for differential specificity on various aspects of anorectic behavior. Correlates of response to treatment will be analyzed. Replication of results will be tested by comparison of the three hospitals.